1. Field of the Invention
The present invention relates to video processing systems. More particularly, the invention concerns a low-cost system for processing and combining video signals, including a bus structure, signal flow, and components having improved power, flexibility, and cost-effectiveness.
2. Description of the Related Art
To produce a composite video image, a video producer may combine two, three, four, or more video images together to produce a single composite scene. A wide variety of effects may be created; for example the producer may require a certain section of an image to be reduced and displayed in a selected region within the composite scene and/or to move across the background. Furthermore, before or after combining the images, the producer may wish to process one or more of the images to provide effects such as morphing, etc.
Conventional video processing systems include a number of specialized separate components, each performing a specific function. A conventional switcher is used to combine video signals from various video sources such as a VCR, a digital disk, or a disk drive, and other video sources, and is used to combine video segments as well as audio. Another component may be connected to provide morphing capability, and still another component may provide other effects. All these independently-designed separate components (which may or may not work well together) are connected together to form a complete system. The conventional switcher is also used to combine video segments with audio. Unfortunately, each component can have high cost and it can be difficult or impossible to coordinate all the components to function in even a minimally cooperative manner, much less in an optimal manner.
Known video production systems are also limited most do not perform processing in "real-time". Real-time processing systems are either not available or only attainable at a high cost (and with limited capability). Therefore such real-time systems are available only to high-end producers such as movie studios. In component-based systems, it may be difficult or impossible to operate all these components simultaneously in real-time.
More particularly, real-time processing is difficult to achieve due to the tremendous amount of processing that goes into creating even a single digital image. Video signals define a frame and each element (e.g. a pixel) within the frame. To define an image moving across a screen, each frame is usually updated at least sixty times per second in order to avoid flicker and other undesirable effects. Due to the number of calculations and processing required to generate such an image, conventional video processing systems necessitate a rendering process before the composite video can be available for viewing, unless the video production system includes an expensive high performance computer with a large and expensive memory. A rendering process can delay viewing the video composite for several seconds or even minutes, thereby effectively preventing real-time editing and all the advantages that go with it.